Interrupter unit for a high-voltage power switch

ABSTRACT

An interrupter unit ( 1 ) for a high-voltage power switch supported by a supporting element ( 5,6 ) radially surrounding the interrupter element ( 1 ) and consisting of two sections ( 5   a   , 5   b   , 6   a,    6   b ). The second section ( 5   b,    6   b ) is radially enlarged in relation to the first section ( 5   a   ,6   a ). A discharge opening ( 10,11 ) for a quenching gas arising during a switching process is disposed between the two sections ( 5   a   , 5   b   , 6   a   , 6   b )

The invention relates to an interrupter unit for a high-voltage circuitbreaker, having two contact pieces which are arranged coaxially oppositein the longitudinal direction and form a switching gap, and having ahollow channel, which runs coaxially with respect to the contact piecesin the longitudinal direction and in whose interior a quenching gasflows along during a switching process in a first direction whichcontinues from the switching gap, and on the outer circumference thequenching gas flows along in a second direction, which is in theopposite direction to the first direction, with at least a part of theinterrupter unit being arranged in a supporting manner, coaxially withrespect to the channel and surrounding it, and with the quenching gasflowing in the second direction being arranged radially, including amounting element.

One such interrupter unit is known, by way of example, from Laid-OpenSpecification DE 32 11 272 A1. In the known arrangement, a part of theinterrupter unit is held by a deflection shroud which acts as a mountingelement. The deflection shroud surrounds a rated current contact piece,which is in the form of a hollow channel. A quenching gas, which isproduced in the switching gap during a switching process, continues toflow through the hollow channel from the switching gap. The quenchinggap is deflected on the deflection shroud, and is passed out of theinterrupter unit outside the hollow channel, in the opposite directionof the flow direction of the quenching gas in the interior of the ratedcurrent contact piece. A design as this has only a relatively shortoutlet flow path for the quenching gas. Furthermore, the quenching gas,which is enriched with decomposition products, is passed out in theimmediate vicinity of the switching gap. The webs which run from theoutlet flow shroud to the rated current contact piece and to which therated current contact piece is fitted are located directly in the outletflow path of the quenching gas, and increase the flow resistance of thispath. With the quenching gas being routed in this way, cooling and rapidonward movement of the quenching gas from the switching gap are possibleonly to a restricted extent.

Furthermore, FIG. 9 in U.S. Pat. No. 4,236,053 discloses an interrupterunit in which the quenching gas flowing away from the switching gap isfirst of all moved away from the switching gap and a labyrinth-likechannel is formed by an arrangement of different outlet flow shrouds, inwhich the quenching gas flow direction is deflected twice through about180°. This results in a relatively long outlet flow path for thequenching gas within a compact area. The outlet flow path there is inthis case substantially formed by attaching deflection shrouds to thecontact pieces, which partially support the interrupter unit. Since thecontact pieces are physically designed as mechanically load-bearingelements which are surrounded by the outlet flow shrouds, thisadmittedly results in optimized arrangements within the interior of theoutlet flow shrouds with regard to the mechanical configuration, but theoutlet flow path has a high flow resistance.

The present invention is based on the object of designing an interrupterunit of the type mentioned initially such that the flow path of thequenching gas from the switching gap to an outlet flow opening has a lowflow resistance, while maintaining a high degree of mechanicalrobustness.

In the case of an interrupter unit of the type mentioned initially, theobject is achieved according to the invention in that the mountingelement has a first section and a second section, which extends radiallyopposite the first section, with the second section being supported bythe first section, and the at least one part of the interrupter unitbeing supported by the second section, and an outlet flow opening, whichpoints in the first direction, for the quenching gas being formedbetween the two sections and in the area of the connection of the firstand second section.

In order to achieve a quenching gas path with improved flowcharacteristics, components which project into it must be removed fromthe outlet flow path. The interrupter unit is supported by an “outercasing body” by the use of a mounting element which surrounds the hollowchannel and has two sections, one of which extends radially, an outletflow opening is formed in the area in which the two sections abut. Theconfiguration of the mounting element as an “outer casing body” createsa space in the interior of the mounting element which is free ofassemblies, and which would necessarily have to be provided formechanical retention. The internal area of the mounting element can befilled or used freely in accordance with the stated requirements for theinterrupter unit. This also results in a better configuration for theoutlet flow path for the quenching gas. The alignment of the outlet flowopening in the first direction, that is to say continuing from theswitching gap, also ensures that the quenching gas cannot flow backdirectly into the area of the switching gap after flowing out of theoutlet flow opening, either, where it would weaken its dielectricstrength.

One advantageous refinement can also be provided by coupling the secondsection to the interrupter unit in the area of a rated current contactpiece.

The coupling of the second section in the area of a rated currentcontact piece results in a very large section of one end of theinterrupter unit being covered by the mounting element, starting fromone end of the interrupter unit and in the longitudinal direction. Acentral mounting point can thus be formed in the area of the ratedcurrent contact piece, in which the entire contact system, with therated current contact, the arc contact, the drives etc, is mounted. Thecoupling may in this case be in the form of a rigid structure or else amoving structure. A moving structure can be provided, for example, for amoving rated current contact piece.

It is advantageously also possible to provide for the second section tobe a part of the current path which can be interrupted by theinterrupter unit.

In order to ensure sufficient mechanical robustness, the second sectionof the mounting element must be produced from a suitable material whichcan at least partially support the interrupter unit. Such materials are,for example, metals, which are also electrically conductive.Particularly when the second section of the mounting element is coupledin the area of a rated current contact piece, the electric current canbe transported via the second part directly to the switching gap. Thereis no need for any additional electrical conductors which would need tobe used to supply the electric current to the contact pieces of theinterrupter unit. As part of the current path to be interrupted, thesecond section of the mounting element also, of course, has to carry theelectrical potential which drives the current. The second section isalso suitable for shielding the assemblies surrounded by it.

A further advantageous refinement provides for a field control electrodeto be arranged on the mounting element, in particular on the secondsection.

Particularly in the end areas of the mounting element, there is a riskof high electrical field strengths occurring, since the transition tofurther assemblies or substances, which may possibly be at a differentelectrical potential, takes place in these areas. Field controlelectrodes can be used to control these electrical fields. In this case,the mounting element may itself be formed such that it forms a fieldcontrol electrode.

A further advantageous refinement provides for a cooling device to bearranged upstream of the outlet flow opening in the course of theflowing quenching gas.

In order to further increase the effectiveness of the long outlet flowpath for the quenching gas, it is particularly advantageous to arrange acooling device in the quenching gas flow. The cooling device reduces thetemperature level of the quenching gas, thus increasing the dielectricstrength of the quenching gas.

One particularly advantageous variant of a cooling device may in thiscase provide for the quenching gas to flow through a perforated metalsheet.

The invention will be described in more detail in the following text,and is illustrated, with reference to an exemplary embodiment, in adrawing, in which the FIGURE shows a schematic design for an interrupterunit for a high-voltage circuit breaker.

The FIGURE shows an interrupter unit 1 for a high-voltage circuitbreaker. The interrupter unit 1 is arranged within an encapsulationenclosure 23, only parts of which are illustrated in the FIGURE. Theencapsulating enclosure 23 is filled with a pressurized insulating gas,for example sulfur hexafluoride. The interrupter unit 1 has a firstelectrical connection 2, as well as a second electrical connection 3 thefirst electrical connection 2 as well as the second electricalconnection 3 are used to link the interrupter unit 1 to an electricalcurrent path, which can be interrupted or made by means of theinterrupter unit 1. The first electrical connection 2 as well as thesecond electrical connection 3 may, for example, be passed by means ofoutdoor bushings through the encapsulating enclosure 23 of thehigh-voltage circuit breaker. The interrupter unit 1 is supported andmounted with respect to the encapsulating enclosure 23 by means ofisolators 4 a, 4 b.

The interrupter unit 1 has a first mounting element 5 as well as asecond mounting element 6. The second mounting element 6 has a flowdeflection device at one end. The first mounting element 5 has aseparate associated flow deflection device 7. The separate flowdeflection device 7 is composed of an insulating material. The firstmounting element 5 as well as the second mounting element 6 have atubular structure, and are each formed from a first section and a secondsection. Furthermore, bodies whose shape is not in the form of acircular tube can also be used to form the mounting elements. The firstsection 5 a of the mounting element 5 has a smaller diameter than thesecond section 5 b of the first mounting element 5. The first section 6a of the second mounting element 6 likewise has a smaller diameter thanthat of the second section 6 b of the second mounting element 6. Thefirst section 5 a and the second section 5 b of the first mountingelement 5 are mechanically coupled to one another in an overlapping area(see the reference symbol 8). The first section 6 a as well as thesecond section 6 b of the second mounting element are likewisemechanically connected to one another in an overlapping area (see thereference symbol 9). The mechanical attachment points 8, 9 are, forexample, arranged at each of three points which are symmetricallydistributed on the circumference of the mounting elements 5, 6. A firstoutlet flow opening 10 for quenching gas is provided between the firstsection 5 a and the second section 5 b of the first mounting element 5.A second outlet flow opening 11 for the quenching gas is providedbetween the first sections 6 a and the second section 6 b. Both thefirst outlet flow opening 10 and the second outlet flow opening 11 havean annular profile, interrupted by the attachment points 8, 9, aroundthe respective first section 5 a, 6 a, and are in the process alignedsuch that the outlet flow openings 10, 11 point away from the switchinggap in the interrupter unit 1. The respective first sections 5 a, 6 asupport the respective second sections 5 b, 6 b. Further attachmentpoints 12 a, 12 b are arranged at that end of the second section 5 b ofthe first mounting element 5 which points towards the switching gap. Anannular fixed contact 13 of a sliding contact arrangement is attached tothe further attachment points 12 a, 12 b. A ratted current contact piece14 is mounted in the fixed contact 13 of the sliding contact arrangementsuch that it can move. A dielectric nozzle 15 is rigidly connected tothe moving rated current contact piece. The dielectric nozzle 15 and themoving rated current contact piece 14 concentrically surround a movingarc contact piece 16. The moving arc contact piece 16 is tubular, andrepresents a hollow channel. The moving rated current contact piece 14,the moving arc contact piece 16 and the dielectric nozzle 15 aresupported by the second section 5 b of the first mounting element 5.

Further attachment points 12 c, 12 d are arranged at that end of thesecond section 6 b of the second mounting element 6 which faces theswitching gap. A stationary rated current contact piece 17 is supportedby the further attachment points 12 c, 12 d. Furthermore, a tubularpiece 18 which forms a channel is held on the further attachment points12 c, 12 d with a stationary arc contact piece 19 being arranged in itsinterior. The stationary arc contact piece 19 projects into thedielectric nozzle 15. The moving rated current contact piece 14 and themoving arc contact piece 16 are arranged coaxially opposite thestationary rated current contact piece 17 and the stationary arc contactpiece 19. The stationary rated current contact piece 17, the stationaryarc contact piece 19 and the tubular piece 18 are supported by thesecond section 6 b of the second mounting element 6.

The second sections 5 b, 6 b are rounded at those ends of the secondsections 5 b, 6 b of the mounting elements 5, 6 which face the switchinggap, where they form a respective field control electrode 5 c, 6 c.

An arc 24 is struck between the two arc contact pieces 16, 19 during aswitching-off movement of the moving arc contact piece 16, of the movingrated current contact piece 14 and of the dielectric nozzle 15 in thedirection of the arrow, which is annotated with the reference symbol 20.The thermal effect of the arc 24 results in a quenching gas being formedin the area of the switching gap formed by the arc contact pieces 16,19, and this quenching gas flows on the one hand through the moving arccontact piece 16 and on the other hand through the tubular piece 18, asa result of the pressure increase produced by the arc 24. The moving arccontact piece 16 has openings at the end facing away from the switchinggap, through which the quenching gas flows out, and strikes the separateflow deflection device 7. The quenching gas is deflected from there, andis deflected outside the moving arc contact piece 16 in the oppositedirection to the direction of the flow of quenching gas in the interiorof the moving arc contact piece 16. The quenching gas flows radiallyoutwards through a radial opening 21 a which is formed by the firstsection 5 a and the second section 5 b, and is then blown out throughthe first outlet flow opening 10.

The quenching gas flowing in the area of the second mounting element 6is guided in an analogous manner. A portion of the quenching gasgenerated in the switching gap is passed through the tubular piece 18from the switching gap, and strikes the deflection device of the secondmounting element 6. From there, it is forced outwards along the outsideof the tubular piece 18 through a radial opening 21 b which is formedbetween the first section 6 a and the second section 6 b of the secondmounting element 6. The second section 6 b in the second mountingelement 6 then results in a further reversal of the flow direction andin the quenching gas being emitted from the second outlet flow opening11, such that the quenching gas is carried away from the switching gap.A cooling device 22 is arranged in the area of the radial opening 21 bwhich is formed between the first section 6 a and the second section 6 bof the second mounting element 6. The cooling device 22 has a tubularstructure, essentially being formed from a perforated metal sheet,through whose holes the quenching gas can pass. The quenching gas iscooled down further as it passes through the holes in the cooling device22.

The arrows which are illustrated by means of interrupted lines in theFIGURE symbolize the path of the quenching gas from the switching gap tothe outlet flow openings 10, 11. The current path from the electricalconnections 2, 3 to the arc contacts 16, 19 and to the rated currentcontacts 14, 17 respectively is represented by the dotted lines.

Since the FIGURE is a schematic illustration, the outlet flow path ofthe quenching gas is illustrated only in principle. In particular, theseparation of the quenching gas flows before and after passing throughthe flow deflection devices can also be achieved by further components.Furthermore, the flow resistance can be minimized by breaking off orrounding body edges.

1. An interrupter unit (1) for a high-voltage circuit breaker, havingtwo contact pieces (16, 19) which are arranged coaxially opposite in thelongitudinal direction and form a switching gap, and having a hollowchannel (18, 16), which runs coaxially with respect to the contactpieces (16, 19) in the longitudinal direction and in whose interior aquenching gas flows along during a switching process in a firstdirection which continues from the switching gap, and on the outercircumference of the channel (18, 16) the quenching gas flows along in asecond direction, which is in the opposite direction to the firstdirection, with at least a part of the interrupter unit (1) beingarranged in a supporting manner, coaxially with respect to the channel(18, 16) and surrounding it, and with the quenching gas flowing in thesecond direction being arranged radially, including a mounting element(5, 6), which, has a first section (5 a, 6 a) and a second section (5 b,6 b), which extends radially opposite the first section (5 a, 6 a), withthe second section (5 b, 6 b) being supported by the first section (5 a,6 a), and the at least one part of the interrupter unit (1) beingsupported by the second section (5 b, 6 b), and an outlet flow opening(10, 11), which points in the first direction, for the quenching gasbeing formed between the two sections (5 a, 5 b) and (6 a, 6 b) in thearea of the connection of the first and second section (8, 9).
 2. Theinterrupter unit (1) for a high-voltage circuit breaker as claimed inclaim 1, characterized in that the second section (5 b, 6 b) is coupledto the interrupter unit (1) in the area of a rated current contact piece(14, 17).
 3. The interrupter unit (1) for a high-voltage circuit breakeras claimed in claim 1 characterized in that the second section (5 b, 6b) is a part of the current path which can be interrupted by theinterrupter unit (1).
 4. The interrupter unit (1) for a high-voltagecircuit breaker as claimed in claim 1 characterized in that a fieldcontrol electrode (5 c, 6 c) is arranged on the mounting element (5, 6)in particular on the second section (5 b, 6 b).
 5. The interrupter unit(1) for a high-voltage circuit breaker as claimed in claim 1,characterized in that a cooling device (22) is arranged upstream of theoutlet flow opening (11) in the course of the flowing quenching gas. 6.The interrupter unit (1) for a high-voltage circuit breaker as claimedin claim 5, characterized in that the cooling device (22) has aperforated metal sheet through with the quenching gas flows.